The effects of planar biaxial strain on the stability, electronic structure, and magnetic properties of monolayer CrS2 systems doped with nitrogen group elements have been investigated based on first principles. Calculations of energy differences, formation energies, bond population, and binding energies indicate the relative stability of the system. Calculations of the electronic structure (energy band structure, density of states, and differential charge density distribution) and magnetic parameters (spin density profiles, single-atom magnetic moments, and total magnetic moments of the system) show that atomic doping in conjunction with strain induces several excellent electronic properties of the system, such as magnetic semiconductors and semimetals. The bandgap of the spin-down channel increases with tensile strain and decreases with compressive strain. In addition, we note that the total magnetic moments of the monolayer CrS2 system and the N atom-doped system decrease with tensile strain and show an increase with compressive strain. The above results provide a reference for further investigation of this material and its application in nanospin devices.